This invention relates generally to photographic printers, and, in particular, relates to a structure and a method of fabrication of a high resolution, linear array, printing head for use in a line printer.
The use of multiple light sources to record information on photographic films is well known. One prior art device is that disclosed by U.S. Pat. No. 3,988,742, titled "Recorder Using Light Emitting Diodes," having a plurality of light emitting diode (LED) units receiving signals from a sampling signal generator. The data is presented as parallel binary signals to the sampling signal generator. A plurality of fiber optic fibers, tapered or untapered, coherent or incoherent, are connected to the LEDs. The outputs of these fibers are arranged in a linear array in a direction transverse to the direction of motion of the recording medium. Focusing means in front of each fiber cause the light to be focused to a point on the recording medium to form a printed element. This array acts as a recording head for the above device.
The density of the printing elements in this linear array is limited by the cross-sectional dimension of the fiber. The use of increasingly thinner fibers to obtain a higher density of printed elements results in increased difficulties in the assembly of the printing head. The precision of alignment becomes more difficult and the fibers break too readily in the assembly process.
The present invention is directed toward providing a printing head in which these undesirable characteristics are minimized.